Co-authors MIŠUREC Josef, MAMUZIC Ilija, HORSINKA Jaromír & JUŘÍČEK Zdeněk

Hot rolling of strips, a crucial flat rolled product, is a key rolling process in manufacturing of steel and non-ferrous products. A majority (75 %) of the strips are then cold rolled. The rest (25 %) is used directly in the form of sheets, bands and coils (obtained by longitudinal and transversal cutting of hot-rolled strips) Cold rolling of very thin strips or foils at temperatures below 0.4 melting temperature is performed in four-high rolling, six-high rolling or even planetary mills. The purpose of this study is to review an original previously constructed model of deformation resistance along the deformation zone. In the reviewed model, the increasing curves of deformation resistance from the plane of entry and plane of exit intersecting at the distance of the rolling force’s arm should be expressed only as functions of the distance from the plane of exit, apart from specific rolling parameters and constants. At present, software packages capable of constructing isosurfaces of stress (and other quantities, such as strain) in cold rolling are available (DEFORM, Forge and others) but no users know what mathematical functions were used. Moreover, for the friction coefficient to be in agreement with a real-world experiment, actual physical modelling in laboratory conditions is required. The exact impacts of forward and backward pulling forces are not included in these programs. An experiment was performed in a four-high rolling mill no. 2 at the company Al Invest Břidličná a.s. with changing the rolling speed and measuring rolling forces (lower speed – slight increase in force), pulling forces (reducing the backward pulling force – marked increase in force) and friction (introducing lubrication with the same roll roughness – notably lower force). The rolled materials were Al99.5, AlMg3, AlCUMg1, AlMn1, including both hardenable materials (normal homogenising temperature 500 °C) and non-hardenable and work-hardened grades. Calculations of mean deformation resistance, diameter of distorted roll and theoretical rolling force were required. The resulting values and graphical plots were focused on the impact of pulling forces and the friction coefficient on deformation resistance along the deformation zone and on the position of the neutral plane.